Added to_simple and to_simple__<fieldname> methods to resources
Update version.
Merge branch 'release/2.1.0' into develop
Send serializer in `to_simple` methods
update version
Merge branch 'release/2.1.1' into develop
Update
update version
Merge branch 'release/2.1.2' into develop
Merge branch 'develop' of github.com:klen/adrest into develop